1. Field of the Invention
This invention relates to a cleaning blade member. More particularly, the present invention relates to a cleaning blade member for removing a toner present on a toner image bearing body, on which a toner image is formed for subsequent transfer to a transfer material, such as a photoconductor or a transfer belt in electrophotography.
2. Description of the Related Art
In the electrophotographic process, a cleaning blade for removing a toner is generally employed for repeated use of an electrophotographic photoconductor or a transfer belt. As a cleaning blade member, polyurethane is used, because polyurethane has satisfactory wear resistance, has sufficient mechanical strength without addition of a reinforcing agent, and is non-polluting. However, the physical properties of polyurethane are known to be temperature-dependent, thereby posing the problem that at high temperatures, the cleaning blade wears.
Among cleaning blades comprising polyurethane is a cleaning blade composed of cured polyurethane having a tensile strength at 50° C. of 12 MPa or more, a tan δ peak temperature of 15° C. or lower, and a hardness of 80° or less. Such a cleaning blade under development is aimed at effectively preventing the chipping of an edge portion in a high temperature environment and showing satisfactory cleaning properties in a broad temperature range, without impairing cleaning properties in a low temperature environment (see Japanese Patent Application Laid-Open No. 2001-265190).
Also available is a blade for an electrophotographic apparatus, which uses a polyurethane sheet obtained by mixing a bifunctional polyol having a number average molecular weight of 1,000 to 3,000 and a trifunctional polyol having a number average molecular weight of 92 to 980 at such a ratio as to provide an average functional group number of 2.02 to 2.20, thereby forming a mixed polyol, mixing a diisocyanate compound having an isocyanate group content of 5 to 20% with the mixed polyol to form a prepolymer, mixing a crosslinking agent, in such an amount as to provide an OH group/NCO group equivalent ratio of 0.90 to 1.05, and a reaction accelerator, in an amount of 0.01 to 1.0 part by weight based on 100 parts by weight of the prepolymer, with the prepolymer, and reacting the mixture (see Japanese Patent Application Laid-Open No. 1997-274416).
However, these blades are not satisfactory, particularly, in terms of wear resistance in a high temperature environment, and further improvements in their properties are desired.
The present invention has been accomplished in light of the above-described circumstances. An object of the present invention is to provide a cleaning blade member excellent in wear resistance even in a high temperature environment.